1. Field of the Invention
The present invention relates to a screen device for displaying an image, in particularly, to a bag type portable screen device in which a screen is equipped with a bag such that the screen is easily assembled to and separated from the bag and has a small volume.
2. Description of the Related Art
A salesman usually carries presentation tools such as a laptop computer, a projector, a screen, and a screen stand for his/her business, and a laptop computer protecting bag and a projector protecting bag are further required to protect the laptop computer and the projector during the carrying of the presentation tools.
Thus, since several presentation tools must be carried simultaneously as described above, the presentation tools, specifically a screen device, are very inconvenient to carry, are very complicated to install and dissemble, and are inconvenient because of a large volume.
Moreover, according to a conventional screen device, a fixed pipe is fixed at the center of the screen device, a spring is installed on the outer circumference of the fixed pipe such that the lateral movement of the spring depends on the fixed pipe when the spring is wound and unrolled, rotary bearings are installed to the lateral sides of the fixed pipe and a rotary rod is further installed on the rotary bearings such that the rotary rod is rotated about the intermediate portion of the fixed pipe by the spring to wind and unroll the screen. Thus, the conventional screen device is relatively strong in comparison to the spring, but its volume is very large due to the complex structure.
Particularly, the conventional rotary rod type screen device is operated by the pressure of the spring and the roll-up movement of the screen is performed by taking the fixed pipe as a base shaft. Thus, if a diameter of the fixed pipe is small, since the horizontal balance of the screen cannot be maintained and the base shaft is bent due to the pressure of the spring, the rotary rod cannot rotate.
Therefore, since the volume of the conventional screen device is much too large to be coupled with a bag.